Round Tube Finishing is an increasing need for manufacturers in many diverse markets. To attend these needs, NS Máquinas has been developing, and joined now to their portfolio, the largest planetary finishing machine, ML350. This machine can work with tubes from OD60mm up to OD356mm.


The concept of planetary system: the abrasive belts rotate around the tube while the feeding rollers are transporting it through the finishing stations of the machine. All ML machines are equipped with this system.

Unlike the centerless system, the planetary concept grants almost no vibration and keeps the temperature to a minimum, preventing material distortion and ensuring a better-quality finishing. It is also possible to finish different shaped tubes, like oval, conic, being them drilled or tapered.


ML350 is born from the need to finish long, large diameters tubes. It’s a one-of-a-kind machine, helping companies being more automated in the finishing process. The reasoning behind the machine is to accomplish the joint venture between a perfect looking finishing, and the safety of the operator.


To feed these large tubes into the machine, two motors with 0.37kW on each side are being used, ensuring enough strength to transport tubes up to 600kg and a two-direction feeding system. While feeding the tube into the machine, ML350 has a photocells system to open the abrasive belts when the tube is entering the orbital wheel, allowing a lifetime increase of this polishing consumable. The 5.5kW motor puts the orbital wheel spinning around the tube and the 15Kw motor runs the 120x2300mm long abrasive belts, making them go up to 25m/s. The large measures of the abrasive belts result in a larger point of contact with the tube, leading to more material removed and less time spent replacing consumables.


And then… things get interesting. ML350, like its younger brother ML300, joins the free belt system (common to all ML machines) with a double pressure roller: Flexibility to cope with out-of-round tubes and stock removal in one finishing machine. The abrasive belts are supported by a double system of 3+1 rollers. 3 main rollers – one to run the abrasive belt, another for diameter adjustment, and the last one for belt tensioning. Then the pressure roller that works as an automatic contact roller. This roller will apply pressure on the tube, enforcing the removal of more material. In the end, the worker can choose whether to use it or not and its tension and the abrasive belt’s flexibility. The result? The grinding pressure you would get with 2 contact grinding rollers (one assembled on each abrasive belt) and the beauty of the planetary system where tube does not spin.


But things don’t end here. With the combination of photocells and a user-friendly programmable software, internally developed, it’s possible to work in 2 different automatic modes: automatic standard and automatic with repetition. In the standard mode, the abrasive belts open automatically for tube entrance, close tight to the tube to make pressure and open just on the very extremity of the product, allowing a complete automatic tube finishing. The automatic mode with repetition allows the tube to pass through the orbital wheel as many times as programed, until reaching the desired finishing. This can be used for high rates of material removal or whenever a fine finishing is required. In this mode, the worker is free to do other jobs while the machine does the work it was programmed for. All the programs can be stored and saved for future uses, making the change of diameters and types of work easier than ever.

Together with this, ML350 features an energy saving mode also, with automatic start and stop. The motors are turned on when needed and turned off automatically as soon the machine detects there is no tube inside. More, the machine shuts down completely after five minutes of inactivity, avoiding unnecessary energy waste.

Finally, in order to increase the machine autonomy, NS MÁQUINAS has been developing and supplying a large number of solutions for tubes automatic loading and unloading. Conveyor systems or bundle type and be integrated to any ML tube finishing machine, including ML350. On the conveyor concept, operator feeds the table with tubes, one by one, being the separated individuate with physical barriers. This method ensures there is no undesired scratches after finishing. On the other hand, the bundle type enables loading and unloading the tubes in a group, leading to great savings in handling and processing time. These loading and unloading systems will increase the time the machine works automatically without any type of intervention, releasing the operator from heavier tasks and contributing also to a higher safety level.


Having all of this, the ML350 is an all-in-one machine that ensures automatization, safety, and a consistent finish in large diameters, long and heavy tubes.


Medical Equipment Tubes Surface Finishing and Polishing

Medical equipment and its metal components are usually subject to strict rules to keep handling and usage as safe as possible. One of our customers in France is a leading producer of medical equipment, and they have come up with a production challenge for us.

curved oval tube before surface finishing

This company has mainly round and oval metal tubes incorporated in the structure of their medical equipment. These tubes are curved and molded into a specific shape. The bending machines’ clamping system often leaves some marks on the surface of the material.

The customer required a smooth surface to send the tubes to be painted afterward. However, it is not possible to send the round and oval tubes directly to the painting process due to the marks caused by the bending process and the irregular surface of the raw material.

This medical equipment producer used a manual grinding process with rotary orbital sanders to remove all the marks and make the surface finishing. It is a very time-consuming job, and the result is not usually uniform.

Considering this, the company reached out to us to find a better solution to replace their current finishing process.

orbital machine results bent tubes

The ML50 curved tubes finishing machine is suitable for round and oval tubes and specially designed for tight curved tube finishing and polishing. This machine’s planetary system allows the work to be done without rotating the tube, delivering the best results on both bent and curved tubes. Therefore, this polishing machine is perfect for products such as water taps and faucets, as well as for finishing handles or polishing curved tubular products.

For this test, we used three different grinding belts: one with a #60 grit, one with a #120 grit, and another made of #scotch. All of them were combined in different ways to provide this customer with the surface finishing combination which best suits their painting needs.

round tube surface polishing

The best combination was the #60-grit belt. It was able to remove all the marks, and then the scotch belt helped achieve a smoother surface. This combination has better chances to work for most tubes.

good quality surface finishing round tubes polishing

Another very important thing worth mentioning is that these tubes are oval, and therefore some sections are completely flat. Since the scotch belt is thicker than an abrasive belt, it becomes essential to execute surface finishing on the flat areas of these tubes. The ML50’s planetary system can adjust the belt even when the tube is not completely round (which is not possible, for example, on centerless systems).

There's also available a wide range of surface finishing and polishing machines for round tubes on our website: https://nsmaquinas.com/categorias/round-tube-finishing-machines/ 

If you have any questions about those finishing machines or need to make some tests please contact us through marketing@nsmaquinas.pt or on our contact page: https://nsmaquinas.com/contacts/



FC120 ZK - Alurodel Case Study Surface Finishing Machine


About Surface Finishing

Metal products usually have visual, aesthetic, or technical specifications related to their surface. Often surface finishing is required to meet those specifications, especially after the raw material has been transported, cut, curved, or drilled. All these processes create scratches, marks, and irregular surfaces which are normally not desirable on the final product. Grinding, chrome-plating, painting, brushing, or polishing are some of the finishes that are commonly seen. For most of these, a belt grinding or brushing process is required.

NS Máquinas produces a wide range of flat surfaces finishing machines equipped with different number of abrasive belt or brush stations are available in different widths and I wet or dry operation. Different options and accessories make these machines suitable for different type of finishing, grinding, and brushing applications, being used on a small production workshop or in a multiple shift production.   

Metal bar raw material without surface finishing
   1) Raw flat bar without surface finishing

flat bar with 60 grit abrasive belt surface finishing
    2) Flat bar after metal grinding process with abrasive belt grit 60

abrasive brush surface finishing on flat metal bar
 3) Flat bar after metal brushing process with an abrasive brush    

Defining a process

Considering the initial surface quality of the material and the required surface level is the most critical step when considering a metal finishing machine. This will determine the right equipment not only for the budget but also for the efficiency of the surface finishing process. NS Máquinas machines can be configurated with a different number of abrasive belts and brush stations. This can lead to a simple and low-cost tube or flat bar finishing machine with a single belt or brush station machine or, on the other limit, to a wet multiple head six stations machine. NS Máquinas can also offer through-feed top and bottom machines or even 4 sides finishing machines. These tubes and bar finishing machines will do 2 sides and even 4 sides simultaneously in one single pass, saving time and material handling costs.


The solution

flat surfaces metal finishing machine

The FC120 ZK machine is a Flat Surface Finishing Machine suitable for stainless steel flat bars and for rectangular tubes. This finishing machine can also process narrow metal sheets, flat metal parts and various other shapes such as door handles, knifes or, door locks.

This machine can be configurated with a single station – abrasive belt – or double station – abrasive belt and an abrasive brush. The 120mm width and 120mm height capacity is enough for most sizes in locksmiths, metal producers, metal finishing companies, metal components producers. The tools free and fast abrasive belt replacement system is an essential feature that allows the operator to quickly change the type of surface and continue with other work. For specific requests, this machine can also include loading and unloading tables, special conveyor belts for not flat components.

Putting the machine in operation and adjusting it was made very easy with a simple control panel where the conveyor belt and abrasive stations are switched on/off and speed adjusted. The machine also counts with a central thickness and pressure adjusting wheel with a 1/10mm precision display.

The model FC120 ZK features a non-woven abrasive brush which applies a smooth and regular finishing to the material. This brush has a wear adjustment wheel which enables a complete use of the abrasive right up to its core.

Below you can find the FC120 ZK demonstration video with rectangular and squared tubes, flat bars, and metal sheets surface finishing. 

The Case Study

Alurodel is a specialized sled manufacturer based in South Tirol, Italy. The aluminum sled is hand-made in their workshop. The company uses high-quality material to avoid rusting, scratching by humidity, or temperature change. Alurodel has purchased 2 months ago one FC120 ZK from NS Máquinas to help them in the finishing operation of aluminium frames.

In fact, at the production, the aluminum frame is one of the parts which requires special attention. Those parts are one of the most exposed to the snow (low temperatures) but also what allows it to slide and support the person's weight.

This company was finishing the aluminum surface to roughness of 3,5µm Ra with manual tools which were a very time-consuming process. NS Máquinas has proposed to achieve the same roughness on an automatic process with FC120 ZK. Setting the machine with a 60-grit abrasive belt and a medium grit abrasive brush, it was easy and quick to achieve a uniform surface which is perfect for the powder coating and clear coat required on the final product. Mr. Torggler, Alurodel general manager, points out that the company has increased 3 times the output of finished material, assuring at the same time a highly consistent production.

Alurodel aluminium sleds are a proven light, flexible, and secure item for pure fun to be used by the whole family. You may know more about this company and their products visiting their website.


Aluminum Sled Producer - aluminum frame surface finishingaluminum sled frame surface finishing


FG170 2ZK - Flat Surfaces Finishing Machine

Rectangular or square tubes and flat bars are used in a lot of different industries: furniture, house appliances, machine manufacturers, civil locksmith, fluid transport systems, handrails producers, glass structures, metal profiles, door locks, automotive, are some of the examples. The use of this shape of metal products depends usually on the appearance, engineering characteristics and or price of raw material.

During the production of the raw material, it hasn't a uniform surface. Then, with the handling to create the rectangular and square tube, the surface is scratched. In most cases, the tube will be used directly in the final product where the surface finishing is not relevant. In other cases, like furniture, handrails it will require some finishing process since the final product will require a good look. This finishing is important for example to apply chroming, painting, material chemical protection, remove cement or rust from old metal tubes to be reused.

The machines usually, on a simple basis, have some tool (like a roller or wheel) applying pressure in the abrasive against the surface of the metal. Other consumables, like abrasive brushes, are also important to increase the finishing result or decrease consumables cost.

NS Máquinas range of polishing machines for rectangular tubes and flat bars are integrated within this type of solutions. The flat surfaces machines have two types of stations: abrasive belt with contact roller (Z stations) and an abrasive brush roller (Z stations).

metal grinding machine for surface finishing with an abrasive belt combined with a contact roller
Abrasive belt combined with contact roller: Z Station 
surface finishing machine for flat surfaces with abrasive brush sctotch brite type
Abrasive brush: K Station

Due to the possibilities of configuration using those stations, NS Máquinas has different polishing machines for each customer requirement. It is possible to have a ZK configuration (one abrasive belt station combined with an abrasive brush station), 2Z (two abrasive belt stations) or 2ZK (two abrasive belt stations combined with one abrasive brush stations).

abrasive belt station combined with abrasive brush station
ZK Version: 1 belt + 1 brush

two abrasive belt stations
2Z Version: 2 abrasive belts

two abrasive belt stations combined with one abrasive brush station for surface finishing
2ZK: 2 abrasive belts + 1 brush
Considering those configurations in the polishing machine, it is possible to achieve a very good surface quality in the rectangular or square tubes ad flat bars. Check the following examples:

metal part after grinding process
square tube polishing

A polishing or finishing machine with several stations and high working capacity needs to have different adjustments mechanisms for the feeding speed, abrasive belt, and abrasive brush speeds, thickness/height, fine pressure adjustments, ammeter to control motors consumption. The FG170 models include a side panel where it is possible to control most of the parameters:

Machine panel control example: on/off buttons for abrasive belt stations, abrasive brush station and conveyor belt; feeding speed selector (with inverter): emergency STOP button; two ammeters for the abrasive belt motors; error light

Depending on the options of the tubes finishing machine, it is possible that this panel includes other buttons and adjustments to control it.
On the front of the machine, there's a wheel to adjust the machine height (set the material thickness):

1/10mm adjustment wheel

The operation on this machine makes a lot of metal dust and residues. NS Máquinas develops all the machines with an integrated circuit inside the machine where it is possible to connect an extraction unit to collect and filter the metal particles and dust. Each station has an individual tube to the exterior:

Inside the machine: three extraction channels in a 2ZK configuration machine
Outside the machine: three extraction points in a three stations machine

Those extraction points can be connected to a single extraction unit with a suitable reduction for the three tubes.
NS Máquinas has different types of dust extractions for different polishing machines:

A Line 
Simple extraction unit with different capacities: from 1700 up to 6800m3/h
AS LineClosed-circuit extraction unit: from 2280 up to 6500m3/h
AW LineWater cyclone system: from 3200 up to 11800m3/h

If you have any questions about those finishing machines or need to make some tests please contact us through marketing@nsmaquinas.pt.


PP220 2K - Mirror Polishing Machine - Rectangular Tubes and Flat Bars

Mirror polishing is the process after grinding and soft polishing. It starts with a good initial finishing of the metal parts. Considering this, it is important to have a machine suitable for your work requirements. NS Máquinas have a variety of machines for the grinding and polishing process: Rectangular Tubes and Flat Bars Finishing Machines. The grinding machines have capacity from 120mm width up to 1100mm, wet or dry versions, different configurations of the abrasive belt and abrasive brush stations and a lot of automatic options. 

Considering this, we suggest three different machines for the preparation of the surface of the metal parts: 
- FC120 ZK: up to 120mm width; dry operation; one abrasive belt station + one abrasive brush station; ideal for small workshops;
FG330 2ZK: up to 330mm width; dry operation; two abrasive belt stations + one abrasive brush station; high width capacity and flexibility with 2+1 stations configuration;
FGW330 3Z: up to 330mm width; wet operation; three abrasive belt stations; effective machine for intensive work and fast grinding/polishing process.

It is critical to test and configure the machines with the proper abrasive belt grits for each type of material and consider the required end result. In those cases, should be used a process with a grit at least until 320, although higher grits allow a better mirror polishing results. 

The PP220 2K is a rectangular tubes mirror polishing machine which is also suitable for flat bars mirror polishing. The machine uses a through feed system combined with two polishing wheels stations. 

The conveyor belt has a 220mm width capacity which is suitable for almost all types of rectangular/square tubes and flat bars. This capacity and design additionally allow to process several tubes at the same time depending on the width of each one. 
The polishing wheels have 400mm diameter and 220mm width dimensions which will decrease the exchange time. It is possible to utilize diverse types of brushes such as: scotch brite, lamella, sisal or cotton buff. Each mirror polishing station is completely independent. The pressure can be adjusted manually by a wheel with an accurate thickness meter of 1/10mm adjustments. In order to achieve the mirror polishing, liquid compound should be used simultaneously with the adequate polishing wheels. Each station includes a 45-liters tank for the liquid compound (for cut motion or color motion). Tanks are connected to a spray gun in each station and controlled in the touchscreen panel (by a timer).

The touchscreen panel included in the machine controls the polishing wheels speed, polishing discs oscillation on/off, conveyor belt speed and monitor motor consumption. 

Consequently, this mirror polishing machine gives a high-quality gloss mirror polishing to the rectangular tubes, flat bars and other flat metal parts. 

tube after mirror polishing process with cotton buff wheel

two cotton buffs wheels for the mirror polishing process

spay gun for liquid compound in the polishing wheels

tanks for the liquid compound - 45 liters capacity

first station with cotton buff wheel for the mirror polishing process

tube after mirror polishing machine

controls of the machine in the touchscreen panel

If you need more help choosing the best machine for you, please check our machine simulator: Find a Product. Nevertheless, if you need direct contact please send an email to marketing@nsmaquinas.pt or contact us through one of the contacts in the contact page: Contacts.